1. Field of the Invention
The present invention relates to an image processing apparatus that performs image processing and an image sensing apparatus such as a digital camera.
2. Description of Related Art
Currently, there are widely spread image sensing apparatuses such as a digital still camera or a digital video camera using a solid state image sensor such as a charge coupled device (CCD) sensor or a complementary metal oxide semiconductor (CMOS) sensor.
In order to obtain a taken image with so-called “bokeh”, which is an image in which a focused subject is clear while other subjects are blur among imaging target objects, namely, an image in which a generally focused subject is emphasized and enhanced, it is necessary to use, for example, an image sensing apparatus having a large size solid state image sensor or an image sensing apparatus having a large diameter lens for imaging a taken image on the solid state image sensor. This type of image sensing apparatus enables imaging with a sufficiently small depth of field, so that a taken image with so-called “bokeh” can be obtained, in which a focused subject is enhanced.
However, when using an image sensing apparatus having a small size solid-state image sensor and a small diameter lens such as a so-called compact type digital camera, imaging with sufficiently small depth of field cannot be performed so that it is difficult to obtain a taken image with “bokeh”. In addition, even if an image sensing apparatus having a large size solid state image sensor and a large diameter lens is used, it is difficult to obtain a taken image in which a focused subject is emphasized by making a luminance difference, a color saturation difference, or the like between the focused subject and other subjects.
Note that there is a conventional method of obtaining an image with “bokeh” by image processing. In this conventional method, first, one reference image data is split into two independent image data, which are image data of a subject area and image data of a background area. Then, a blurring process is performed on the sprit background image data, and then the background image data after the blurring process and the reference image data are combined. After the combining process, an anti-aliasing process is performed for preventing a boundary between the background area and the subject area from appearing jaggy and hence unnatural. Thus, an attempt is made to obtain an image with “bokeh”. Even if an image with “bokeh” could be obtained by the conventional method, the complicated process described above would be necessary.